PARP1 and infection: In this study, infection with Ad-PARP1 increased luciferase activity driven by six tandem repeats of the AP1-binding site (6×AP1), while infection with adenovirus encoding a mutant PARP1 lacking enzymatic activity (Ad-mut-PARP1) did not (Fig. 7a), indicating that enzymatic activity was indispensable for PARP1-induced c-Jun transactivation.